The present invention relates to dropout compensation of a sampled television signal, and more particularly, to a method wherein the severity of the dropout determines the dropout concealment method used.
A U.S. Pat. No. 4,470,065 entitled "Adaptive Error Concealment Using Horizontal Information Determination from Adjacent Lines" filed Mar. 25, 1982, in the name of G. A. Reitmeier and assigned to the assignee of the present invention describes a method of adaptive dropout compensation for dropouts which affect a portion of the samples, said portion occurring over a duration of less than one television line in the displayed picture, while another previous application entitled "Interleaved Recording Format for Digital Video," Ser. No. 241,925, filed Mar. 9, 1981 and assigned to the assignee of the present invention, now U.S. Pat. No. 4,393,414, describes a method of formatting component video on tape so that dropouts occur in an interleaved pattern. In an actual DVTR (digital video tape recorder), the majority of dropouts will be of duration less than one line, and can be concealed using the adaptive technique of said first filed application. However, some dropouts of longer duration may occur, and it's essential that none of these dropouts results in a noticeable flash on the screen, as could occur when an adaptive technique is used with erroneous pixels that are proximate the erroneous pixel to be concealed. Hence, it is important to match the method of error concealment with the severity of the tape dropout, since high quality concealment is desirable for the many small errors, while a lower quality concealment can be used for very large errors. This is because small dropouts leave more adjacent data (valid pixels) with which to obtain a good replacement pixel, while concealment algorithms that handle large, e.g. greater then one horizontal line, dropouts cannot take advantage of that fact.
It is therefore desirable to provide a dropout concealment system where the concealment method is determined by the severity of the dropout.